“Microsoft may make strategic decisions or changes that may be detrimental to us. For example, in addition to the Surface tablet, Microsoft may broaden its strategy to sell other mobile devices under its own brand, including smartphones,” the company wrote in the filing. “This could lead Microsoft to focus more on their own devices and less on mobile devices of other manufacturers that operate on the Windows Phone platform, including Nokia.”

BGR exclusively reported last fall that Microsoft was developing a self-branded smartphone that could be released in the coming months. The handset is rumored to be equipped with a display between 4-inches and 5-inches, and will compete directly with other high-end devices such as the iPhone 5 and Galaxy S III.